[RFC PATCH V2 1/9] io_uring: add io_link_req() helper

[Ming Lei <ming.lei@redhat.com>]

Add io_link_req() helper, so that io_submit_sqe() becomes more readable.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 io_uring/io_uring.c | 41 +++++++++++++++++++++++++++--------------
 1 file changed, 27 insertions(+), 14 deletions(-)

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 2675cffbd9a4..c02c9291a2df 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -2172,19 +2172,11 @@ static __cold int io_submit_fail_init(const struct io_uring_sqe *sqe,
 	return 0;
 }
 
-static inline int io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
-			 const struct io_uring_sqe *sqe)
-	__must_hold(&ctx->uring_lock)
+/*
+ * Return NULL if nothing to be queued, otherwise return request for queueing */
+static struct io_kiocb *io_link_sqe(struct io_submit_link *link,
+				    struct io_kiocb *req)
 {
-	struct io_submit_link *link = &ctx->submit_state.link;
-	int ret;
-
-	ret = io_init_req(ctx, req, sqe);
-	if (unlikely(ret))
-		return io_submit_fail_init(sqe, req, ret);
-
-	trace_io_uring_submit_req(req);
-
 	/*
 	 * If we already have a head request, queue this one for async
 	 * submittal once the head completes. If we don't have a head but
@@ -2198,7 +2190,7 @@ static inline int io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
 		link->last = req;
 
 		if (req->flags & IO_REQ_LINK_FLAGS)
-			return 0;
+			return NULL;
 		/* last request of the link, flush it */
 		req = link->head;
 		link->head = NULL;
@@ -2214,9 +2206,30 @@ static inline int io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
 fallback:
 			io_queue_sqe_fallback(req);
 		}
-		return 0;
+		return NULL;
 	}
+	return req;
+}
+
+static inline int io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
+			 const struct io_uring_sqe *sqe)
+	__must_hold(&ctx->uring_lock)
+{
+	struct io_submit_link *link = &ctx->submit_state.link;
+	int ret;
 
+	ret = io_init_req(ctx, req, sqe);
+	if (unlikely(ret))
+		return io_submit_fail_init(sqe, req, ret);
+
+	trace_io_uring_submit_req(req);
+
+	if (unlikely(link->head || (req->flags & (IO_REQ_LINK_FLAGS |
+				    REQ_F_FORCE_ASYNC | REQ_F_FAIL)))) {
+		req = io_link_sqe(link, req);
+		if (!req)
+			return 0;
+	}
 	io_queue_sqe(req);
 	return 0;
 }
-- 
2.42.0